Wireless devices and radiating systems for them typically operate one or more cellular communication standards and/or wireless connectivity standards, each standard being allocated in one or more frequency bands, and said frequency bands being contained within one or more regions of the electromagnetic spectrum. Examples for such wireless devices include a mobile phone, a smartphone, a PDA, an MP3 player, a headset, a USB dongle, a laptop computer, a gaming device, a digital camera, a PCMCIA or Cardbus 32 card, or generally a multifunction wireless device.
The invention relates in particular to wireless devices (and radiating systems), which can perform in two or more separate frequency regions (bands) of the electromagnetic spectrum. They are generally referred to as multi-band devices (radiating systems), and are in particular for example referred to as dual-band (working in two frequency bands), tri-band (working in three frequency bands), quad-band (working and four frequency bands) and penta-band (working in five frequency bands). Standards, according to which such wireless devices (radiating systems) may operate, comprise for example UMTS, GSM (e.g., GSM850, GSM900, GSM1800, GSM1900) and LTE (e.g., LTE700, LTE2300, LTE2500). The necessary frequency bands may thus, for example, comprise the frequency regions in the areas from 800 MHz to 960 MHz and from 1710 MHz to 2690 MHz, or from 698 MHz to 960 MHz and from 1710 to 2690 MHz.
It is known in the art to use wireless devices (radiating systems) that do not require the use of a separate antenna element, but rather use a ground plane layer providing a determined radioelectric performance in one or more frequency regions of the electromagnetic spectrum. Such devices are also referred to as antennaless devices because they do not have a separate antenna element. Such devices (radiating systems) are, for example, known from co-owned applications WO2010/15365, WO2010/15364, WO 2014/012796 and U.S. Ser. No. 14/807,449. The disclosures of the aforementioned co-owned applications are herewith incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control.
Such (antennaless) devices typically comprise a radiating system capable of transmitting and receiving electromagnetic wave signals in at least two frequency regions. The radiating system comprises a radiating structure comprising at least one ground plane layer and at least one boosting element. The radiating system further comprises a radiofrequency system. The radiofrequency system is suitable to modify the impedance of the radiating structure to provide impedance matching to the radiating system in the at least first and second frequency regions of operation of the radiating system.
In well matched radiating systems, the reflection coefficient may have a value of approximately −4 dB or less, for example −4.5 dB or less, in particular −6 dB or less in the frequency region in which the wireless device operates. In other well matched radiating systems, the voltage standing wave ratio (VSWR) may be 4.5 or less, in particular 4 or less. Such radiofrequency systems typically provide their impedance matching by using a radiofrequency system with long and complex matching networks of electronic components comprising a large number of passive reactive components, for example 6 or more components. Such radiofrequency systems are known, for example, from the above-mentioned, co-owned applications. In addition to the matching network, the radiofrequency system may, for example, comprise additional switches, diodes or other elements or no other elements, i.e., the radiofrequency system may consist of the matching network.